/*
 * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 1999-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: ThreadControllerWrapper.java,v 1.2.4.1 2005/09/15 08:15:59 suresh_emailid Exp $
 */
package com.sun.org.apache.xml.internal.utils;

/**
 * A utility class that wraps the ThreadController, which is used
 * by IncrementalSAXSource for the incremental building of DTM.
 */
public class ThreadControllerWrapper {

    /** The ThreadController pool   */
    private static ThreadController m_tpool = new ThreadController();

    public static Thread runThread(Runnable runnable, int priority) {
        return m_tpool.run(runnable, priority);
    }

    public static void waitThread(Thread worker, Runnable task) throws InterruptedException {
        m_tpool.waitThread(worker, task);
    }

    /**
     * Thread controller utility class for incremental SAX source. Must
     * be overriden with a derived class to support thread pooling.
     *
     * All thread-related stuff is in this class.
     */
    public static class ThreadController {

        /**
         * This class was introduced as a fix for CR 6607339.
         */
        final class SafeThread extends Thread {
            private volatile boolean ran = false;

            public SafeThread(Runnable target) {
                super(target);
            }

            public final void run() {
                if (Thread.currentThread() != this) {
                    throw new IllegalStateException("The run() method in a" + " SafeThread cannot be called from another thread.");
                }
                synchronized (this) {
                    if (!ran) {
                        ran = true;
                    } else {
                        throw new IllegalStateException("The run() method in a" + " SafeThread cannot be called more than once.");
                    }
                }
                super.run();
            }
        }

        /**
         * Will get a thread from the pool, execute the task
         *  and return the thread to the pool.
         *
         *  The return value is used only to wait for completion
         *
         *
         * NEEDSDOC @param task
         * @param priority if >0 the task will run with the given priority
         *  ( doesn't seem to be used in xalan, since it's allways the default )
         * @return  The thread that is running the task, can be used
         *          to wait for completion
         */
        public Thread run(Runnable task, int priority) {

            Thread t = new SafeThread(task);

            t.start();

            //       if( priority > 0 )
            //      t.setPriority( priority );
            return t;
        }

        /**
         *  Wait until the task is completed on the worker
         *  thread.
         *
         * NEEDSDOC @param worker
         * NEEDSDOC @param task
         *
         * @throws InterruptedException
         */
        public void waitThread(Thread worker, Runnable task) throws InterruptedException {

            // This should wait until the transformThread is considered not alive.
            worker.join();
        }
    }

}
